SU671253A1 - Method of producing 2,3-dihydrofurane or 4,5-dihydro-2-methyl furan - Google Patents

Description

I

The invention relates to a new process for the preparation of 2,3-dihydrofuran or 4,5-1-hydro-2-methylfuran (2,3-dihydrosilvana).

These compounds are valuable starting materials for the synthesis of biologically active compounds and polymeric materials.

A known method for producing 2,3-dihydrofurans by hydrogenating furan or its alkyl derivatives in a solution of pentane in the presence of dimethylformamide as a modifier for ruthenium al-. mini catalyst sh.

This method has a low yield of the target product 6.2 for the reacted raw materials, complex instrumentation due to the need for increased pressure, high fire and explosiveness due to the use of hydrogen, the need for a modifier.

The purpose of the invention is to simplify the process technology and increase the yield of the target product.

This is achieved by the fact that tetrahydrofuran or 2-methyltetrahydrofuran is subjected to dehydrogenation at 2OO-350 ° C in the vapor-gas phase on a chromcyan oxide-coarse oxide catalyst.

In addition, the process can be carried out in an environment of benzene.

The catalyst is obtained by displacing aqueous solutions of ammonium chromate and zinc, manganese, and aluminum sulphate, followed by neutralization of the reaction mass with an aqueous solution of ammonia and displacing the resulting precipitate with an aqueous solution of potassium carbonate and calcining, with the addition of alumina being 1-2 wt. %

The method can be carried out in pulsed (example J. and 2) and flow (examples 3 and 4) modes of operation.

The furan and dihydrofuran formed in the dehydrogenation of tetrahydrofuran are separated from the reaction mixture by conventional methods, for example by distillation and rectification. Unreacted tetrahydrofuran in a solution of benzene vovra.;. Shyut in recycling.

Thus, for example, the rectification of the South dihydrofuranate raw material consisting of 48% tetrahydrofuran, 35% dihydrofuran and 17% furman on a laboratory rectification, 30 theoretical plates, with a reflux ratio of 15, 3.2 g of the boiling fraction at 54.3 were isolated - 54, consisting of 99.9% of dihydrofuran and O, 1% of furan.

Example 1. To a catalytic tube with O, 3 g of an oxide chrom-zinc-manganese one promoted with alkaline additives, a catalyst prn 2SO C and an argon gas with a speed of 60 ml / min are fed with 3 ml of tetrahydrofuran. Conversion of tetragvdrofuran 26.66%, the output of dihydrofuran 17.7% | furan yield of 7.9% for missed TV-ravvdrofuran.

Example 2 Into the catalytic tube under the above conditions, 3 ml of tetrahydrosylvanes are fed, Conversion of Tatrahydrosylvanes 21.4%, yield

12534

I 2,3-dihydrosylvana 13.6%, the yield of sylvan 7.87. To missed tetrahydrosilvan.

Example 3. A cataltic J tube with 4 ml of catalyst was fed with 2.7 g / h of a 20% solution of tetrahydrofuran in benzene in a stream of argon (150 ml / min). At 258 C, conversion of tetrahydrofuran is 5.0%, the yield of dihydrofuran and furan is 10 missing tetrahydrofuran 3, O% and 1.9%, respectively, to the reacted tetrahydrofuran 6O% and 38%, respectively.

15 Example 4. 2.7 g / h of a 20% solution of tetrahydrofuran in benzene in a stream of argon (150 ml / min) are fed through a catalytic tube with 40 ml of catalyst. At 293 ° C convert

20 tetragvdrofuran 4, O%, vykod aigidrofurana and furan, reacted tetrahydrofuran 2.6% and 1.2%, respectively, 65% and 30% reacted tetrahydrofuran,

25 The results are shown in table.

furan pentane

2.7 142

20 26, 3

Conversion of the original product,%

The output of adhydrofuran on the missing raw material,%

The output of dihydrofuran on the reacted raw materials,%

oxide chromium

zincmarganese

tetrahydrofuran

benzene

enzol

ABOUT

293

258

ABOUT

20 4,0

20 5.0

2.6

3, O

Claims (2)

65 6O 567 Claim 1. The method of preparation of 2,3-dihydrofuran or 4,5-dihydro-2-methylfuran, characterized in that, in order to simplify the process technology and increase the yield of the target product, tetrahydrofuran or methyltetrahydrofuran is subjected to dehydrogenation at 200 350 ° C in vapor-gas phase on oxide chromium-manganese catalyst, 12536 2. The method according to p. 1, I distinguish. Shch and with the fact that the process is carried out in the environment of benzene, s Sources of information taken into account in the examination 1. US patent No. 3828О77, cl. 26O-3. 46.1, published 06,08,74. 2, Copyright certificate -SSSR Yu No. 305906, class, B 01 L 37/04, 11.05.70,